1. Field of the Invention
The present invention relates to cyclopentane heptenoic acid-5-cis-2-(3α-hydroxy or lower alkyloxy-5-thienylpentyl)-3,5-dihydroxy, [1α,2β,3α,5α] compounds lower alkyl, hydroxyl lower alkyl and indole lower alkyl amides and esters thereof as potent ocular hypotensives that are particularly suited for the management of glaucoma.
2. Description of Related Art
Ocular hypotensive agents are useful in the treatment of a number of various ocular hypertensive conditions, such as post-surgical and post-laser trabeculectomy ocular hypertensive episodes, glaucoma, and as presurgical adjuncts.
Glaucoma is a disease of the eye characterized by increased intraocular pressure. On the basis of its etiology, glaucoma has been classified as primary or secondary. For example, primary glaucoma in adults (congenital glaucoma) may be either open-angle or acute or chronic angle-closure. Secondary glaucoma results from pre-existing ocular diseases such as uveitis, intraocular tumor or an enlarged cataract.
The underlying causes of primary glaucoma are not yet known. The increased intraocular tension is due to the obstruction of aqueous humor outflow. In chronic open-angle glaucoma, the anterior chamber and its anatomic structures appear normal, but drainage of the aqueous humor is impeded. In acute or chronic angle-closure glaucoma, the anterior chamber is shallow, the filtration angle is narrowed, and the iris may obstruct the trabecular meshwork at the entrance of the canal of Schlemm. Dilation of the pupil may push the root of the iris forward against the angle, and may produce pupilary block and thus precipitate an acute attack. Eyes with narrow anterior chamber angles are predisposed to acute angle-closure glaucoma attacks of various degrees of severity.
Secondary glaucoma is caused by any interference with the flow of aqueous humor from the posterior chamber into the anterior chamber and subsequently, into the canal of Schlemm. Inflammatory disease of the anterior segment may prevent aqueous escape by causing complete posterior synechia in iris bombe, and may plug the drainage channel with exudates. Other common causes are intraocular tumors, enlarged cataracts, central retinal vein occlusion, trauma to the eye, operative procedures and intraocular hemorrhage.
Considering all types together, glaucoma occurs in about 2% of all persons over the age of 40 and may be asymptotic for years before progressing to rapid loss of vision.
Certain eicosanoids and their derivatives have been reported to possess ocular hypotensive activity, and have been recomended for use in glaucoma management. Eicosanoids and derivatives include numerous biologically important compounds such as prostaglandins and their derivatives. Prostaglandins can be described as derivatives of prostanoic acid which have the following structural formula:

Various prostaglandin derivatives, e.g. latanoprost, travoprost, unoprostone isopropyl, etc. have been commercialized for lowering intraocular pressure and managing glaucoma. Recently, a prostamide, i.e. bimatoprost, has been marketed for treating increased eye pressure caused by open-angle glaucoma or ocular hypertension. Prostamides are structurally similar to prostaglandins but are biologically different. Prostamides, unlike prostaglandins, do not lower intraocular pressure by interaction with the prostaglandin receptor. (See U.S. Pat. No. 5,352,708, which hereby is incorporated by reference in its entirety.)
While prostaglandins and prostamides are effective in lowering intraocular pressure without significant intraocular side effects, ocular surface (conjunctival) hyperemia and foreign-body sensation have been associated with the topical ocular use of such compounds, in particular PGF2α and its prodrugs, e.g., its 1-isopropyl ester, in humans.
Thus, it would be desirable to discover a prostamide or prostaglandin compound which effectively lowers intraocular pressure while not causing excessive hyperemia.